Thanks to Radhika Gupta, a former graduate student at the University of Utah who prepared our poster from scratch!

Of coarse! Quasi-isometries and groups: rigidity and classification

Ventotene (LT), Italy, 9-14 September, 2019

The conference took place in Ventotene (LT), Italy, from the 9th until the 14th of September 2019.


Martin Bridgeman (Boston College)

Anna Erschler (ENS Paris)

Stefano Francaviglia (Università di Bologna)

Roberto Frigerio (Università di Pisa)

Alessandra Iozzi (ETHZ)

Fanny Kassel (IHES and CNRS)

Michah Sageev (Technion)

Scientific program

There were the following mini courses:
  • Quasi-isometric rigidity for certain classes of solvable groups                                         (Tullia Dymarz, University of Wisconsin) [abstract]
  • The asymptotic geometry of certain Artin groups                                                              (Jingyin Huang, Ohio State University) [abstract]
  • Analysis on boundaries of hyperbolic groups                                                                       (John MacKay, University of Bristol) [abstract]

In addition to the minicourses there were three 75' morning talks to complement the minicourses and nine 45' afternoon talks.

Morning speakers: 

  • Christopher Cashen, Universität Wien (Jingyin Huang's minicourse)
  • David Hume, University of Oxford (John MacKay's minicourse)
  • Xiangdong Xie, Bowling Green State University (Tullia Dymarz's minicourse)

Afternoon speakers: 

  • Jérémie Brieussel, Université de Montpellier
  • Ruth Charney, Brandeis University
  • François Dahmani, Université de Grenoble Alpes
  • Peter Haissinsky, Université de Aix-Marseille
  • Ursula Hamenstädt, Universität Bonn (TBC)
  • Enrico Le Donne, Università di Pisa and Jyväskylän Yliopisto
  • Gabriele Link, Karlsruhe Institut für Technologie
  • Sara Maloni, University of Virginia
  • Katie Vokes, Institut des Hautes Études Scientifiques

Lightning talks:

  • Radial property RD versus property RD (Adrien Boyer, Antoine Pinochet-Lobos and Christophe Pittet)
  • Finiteness properties of totally disconnected locally compact groups (Ilaria Castellano)
  • QI-classification and bounded cohomology (James Farre)
  • Cross-ratio no cube complexes and length spectrum rigidity (Elia Fioravanti, Jonas Beyrer)
  • Density of eigenvalues, cutoff of random walks and almost diameter of a graph (Kostantin Golubev and Amitay Kamber)
  • Cannon-Thurston maps for CAT(0) groups with isolated flats (Radhika Gupta)
  • Quasi-isometric rigidity beyond groups (Tobias Hartnick)
  • Spaces of discrete subgroups and applications (Yannick Krifka)
  • Topological full groups and completions of Thompson's V (Waltraud Lederle)
  • Sealed groups (Elyasheev Leibtag)
  • Comparing the Roller and B(X) boundaries of CAT(0) cube complexes (Ivan Levcovitz)
  • Quasi-isometry classification of RAAGs that split over abelian subgroups (Alex Margolis)
  • Multicomplexes, bounded cohomology and simplicial volume (Roberto Frigerio and Marco Moraschini)
  • Monodromy irreducibility as a group invariant for free-by-cyclic groups (Jean-Pierre Mutanguha)
  • Triangular and friendly relationships between groups, coarse geometry and coarse analysis (Adrien Boyer and Jean-Claude Picaud)
  • Sublinear boundaries of CAT(0) groups (Kasra RafiYulan Qing and Giulio Tiozzo)
  • Compact hyperbolic manifolds without spin structures (Bruno Martelli, Stefano Riolo and Leone Slavich)
  • Convex projective Dehn fillings of dimension four (Gye-Seon Lee, Ludovic Marquis and Stefano Riolo)
  • One-dimensional action of Higman group (Cristobal Rivas and Michele Triestino)
  • The local to global property in spaces with hyperbolic directions (Jacob Russel-Madonia, Davide Spriano and Hung C. Tran)
  • Cut and paste between surface branched covers (Stefano Francaviglia  and Filippo Sarti)
  • Quasi-isometric non-rigidity for group actions (David Kielak and Damian Sawicki)
  • Relative Lp-cohomology and Heintze groups (Emiliano Sequeira)
  • From hyperbolic to hyerarchically hyperbolic (Davide Spriano)
  • Envelopes in Outer Space (Christian Steinhart)
  • Formal languages in geometric group theory (Hang Lu Su)
  • Volumes of random 3-manifolds (Gabriele Viaggi)
  • Densities non-realisable as the Jacobian of a bi-Lipschitz map are generic (Rodolfo Viera)


  1. Sebastian Baader (Universität Bern)
  2. Marco Barberis (University of Warwick)
  3. Giuliano Basso (ETH Zürich)
  4. Ludovico Battista (Università di Pisa)
  5. Adrien Boyer (Université de Paris Diderot)
  6. Martin Bridgeman (Boston College)
  7. Jérémie Brieussel (Université de Montpellier)
  8. Cristopher Cashen (Universität Wien)
  9. Ilaria Castellano (Università di Udine)
  10. Nicola Cavallucci (Sapienza Universi†à di Roma)
  11. Ruth Charney (Brandeis University)
  12. Fabienne Chouraqui (University of Haifa at Oranim)
  13. Matt Cordes (ETH Zürich)
  14. François Dahmani (Université Grenoble Alpes)
  15. Luca De Rosa (ETH Zürich)
  16. Valentina Disarlo (Universität Heidelberg)
  17. Tullia Dymarz (University of Wisconsin at Madison)
  18. Gianluca Faraco (TIFR Mumbai)
  19. James Farre (Yale University)
  20. Tom Ferragut (Université de Montpellier)
  21. Leonardo Ferrari (Università di Pisa)
  22. Elia Fioravanti (University of Oxford)
  23. Xenia Flamm (ETH Zürich)
  24. Francesco Fournier Facio (ETH Zürich)
  25. Stefano Francaviglia (Università di Bologna)
  26. Roberto Frigerio (Università di Pisa)
  27. Giles Gardam (Universität Münster)
  28. Tommaso Goldhirsch (ETH Zürich)
  29. Konstantin Golubev (ETH Zürich)
  30. Daniel Groves (University of Illinois at Chicago)
  31. Vincent Guirardel (Université de Rennes I)
  32. Radhika Gupta (Technion)
  33. Peter Haissinsky (Université de Aix-Marseille)
  34. Ursula Hamenstädt (Universität Bonn)
  35. Nima Hoda (University Wroclaw)
  36. Jingyin Huang (Ohio State University) 
  37. David Hume (University of Oxford)
  38. Merlin Incerti-Medici (Universität Zürich)
  39. Alessandra Iozzi (ETH Zürich)
  40. Agnese Janigro (Università di Milano Bicocca)
  41. Autumn Kent (University of Wisconsin at Madison)
  42. Steve Kerckhoff (Stanford University)
  43. Alice Kerr (University of Oxford)
  44. Ville Kivioja (Jyväskylän Yliopisto)
  45. Yannick Krifka (ETH Zürich)
  46. Maria Gabriella Kuhn (Università di Milano Bicocca)
  47. Nir Lazarovich (Technion)
  48. Enrico Le Donne (Università di Pisa and Jyväskylän Yliopisto)
  49. Waltraud Lederle (Université Catholique de Louvain)
  50. Ivan Levcovitz (Technion)
  51. Gabriele Link (Karlsruhe Institute für Technologie)
  52. John MacKay (University of Bristol)
  53. Sara Maloni (University of Virginia)
  54. Jason Manning (Cornell University)
  55. Alex Margolis (Technion)
  56. Bruno Martelli (Università di Pisa)
  57. Concita Martinez Perez (Universidad de Zaragoza)
  58. Marco Moraschini (Universität Regensburg)
  59. Andrés Navas (Universidad de Santiago de Chile & Universidad Nacional Autónoma de México)
  60. Irene Pasquinelli (Sorbonne Université)
  61. Jean-Claude Picaud (Universität Zürich)
  62. Yulan Qing (University of Toronto)
  63. Kasra Rafi (University of Toronto)
  64. Lisa Ricci (ETH Zürich)
  65. Stefano Riolo (Université de Neuchâtel)
  66. Cristobal Rivas (Universidad de Santiago de Chile)
  67. Jacob Russel (CUNY Graduate Center)
  68. Michah Sageev (Technion)
  69. Andrea Sambusetti (Sapienza Università di Roma)
  70. Filippo Sarti (Università di Bologna)
  71. Paul Schupp (University of Illinois at Urbana-Champaign)
  72. Emiliano Sequeira (Université de Lille & Universidad de la República)
  73. Davide Spriano (ETH Zürich)
  74. Micki Soule (University of Wisconsin at Madison)
  75. Christian Steinhart (Universität Saarland)
  76. Hang Lu Su (ICMAT)
  77. Paula Truöl (ETH Zürich)
  78. Constantin Vernicos (Université de Montpellier)
  79. Gabriele Viaggi (Universität Bonn)
  80. Rodolfo Viera (Universidad de Santiago de Chile)
  81. Federico Vigolo (Weizmann Institute of Science)
  82. Katie Vokes (IHES)
  83. Thomas Weigel (Università di Milano Bicocca)
  84. Xiangdong Xie (Bowling Green State University)


We gratefully acknowledge the support of:

  • the Zürich Graduate School of Mathematics
  • the USA National Science Foundation
  • Anna Erschler's European Research Council GrolsRan grant
  • the GNSAGA from the Istituto Nazionale di Alta Matematica
  • Fanny Kassel's European Research Council DiGGeS grant
  • the FNR of Jean-Marc Schlenker's and the Université de Luxembourg
  • the project Jeune Géomètres of the Fondation Louis D.
  • the Swiss Mathematical Society
  • the Department of Mathematics of the Università di Bologna
  • Bruno Martelli's research funds
  • the  Stiftung zur Förderung der mathematischen Wissenschaften in der Schweiz


The workshop was organised with the patronage of the Comune di Ventotene.